Ok i've done it and it works without more hardware! Only the one in the original thread of Ibersystem:
Now i want to share some information with you, mikrotik users.
1) I can see loadbalancing working with LACP only when i test with more than one host in LAN1.
2) Loadbalancing is not 50%/50%, it's more a 80%/20%. Do you have some best result in your experience?
3) I have configured LACP in the two switches and LLDP [the two in active mode, is this correct??]
4) When i use discovery with winbox i can see only two of the four RB that form the wifi-bridge.
5) I've build the wifi-bridge with EOIP and not WDS. Does someone have experience of WDS working in this scenario?
6) I've to disable in ALL the switches and bridges protocol RSTP. With RSTP enable only a channel work.
7) When i start the entire system i've got to wait like 3 o4 minutes until all go right.